Exceed data usage charge?

OK. I leave in a share house, and I believe our broadband is ADSL 200GB. I saw the bill from owner last time. In the past few months, we had several months that ran out the data usage. I remember one time the owner was angry and told us Telstra would charge $3000 for 30GB extra data usage after exceeded 200GB limit (In the other words, charge $0.1 per MB). Which is unacceptable, and surely we wouldn't/couldn't pay it. Owner said he will figure it out. I just wonder, does Telstra actually charge 1 dollar per MB for exceeding data limit? Is Telstra lying? or the owner?